What is a defining feature of fast twitch fibers regarding endurance capacity?

Fast twitch muscle fibers, also known as Type II fibers, are characterized by their ability to generate rapid and powerful contractions but have a limited capacity for endurance. This is primarily due to their reliance on anaerobic metabolism, which allows for quick bursts of energy but leads to quicker accumulation of metabolic byproducts, such as lactic acid. As a result, these fibers fatigue quickly, making them less suitable for activities requiring prolonged effort.

The defining feature of fast twitch fibers is their low endurance capacity. They are optimized for high-intensity, short-duration activities, such as sprinting or weightlifting, where quick power output is essential. This fiber type is less effective for longer, more sustained activities, which typically rely on slow twitch fibers that are more efficient at utilizing oxygen and have greater endurance.

The other options describe characteristics not associated with fast twitch fibers. For example, high endurance capacity in muscle fibers would indicate a preference for slow twitch fibers designed for prolonged, less intense activities.